1. Field of the Invention
The present invention relates to a cooling apparatus, and more particularly, to a cooling apparatus for a system including a heat source, and a method for controlling the cooling apparatus.
2. Discussion of the Related Art
A variety of systems such as computers, projectors, and projection type television receivers inevitably have heat sources. Heat generated from such a heat source should be effectively dissipated, in order to enable the associated system to operate normally, and to prevent elements arranged around the heat source from being damaged due to the heat.
In order to dissipate heat generated from a heat source, namely, to cool the heat source, a forced convection air cooling system is mainly used which forcibly circulates air by forced convection, using a cooling fan.
The most fundamental factors to be reviewed or estimated in designing a forced convection air cooling system are the amount of heat generated from a heat source and the amount of air required to completely dissipate the generated heat. These factors depends on the following Expression 1:Q={dot over (m)}·Cp·ΔT  [Expression 1]where, “Q” represents the amount of heat generated from a heat source, “{dot over (m)}” represents a mass flow rate of air, “Cp” represents specific heat, and “ΔT” represents the temperature difference between air supplied to cool the heat source and air discharged after being used to cool the heat source.
When the mass flow rate {dot over (m)} in Expression 1 is converted to a volume flow rate, the following Expression 2 is obtained:Q=ρ·{dot over (V)}·Cp·ΔT  [Expression 2]where, “ρ” represents the density of air, and “{dot over (V)}” represents a volume flow rate of air.
Expression 2 can be rearranged as the following Expression 3:
                              V          .                =                  Q                                    ρ              ·                              C                p                            ·              Δ                        ⁢                                                  ⁢            T                                              [                  Expression          ⁢                                          ⁢          3                ]            
Referring to Expression 3, it can be seen that the volume flow rate of air, {dot over (V)}, required to cool a system, in which the heat source is arranged, is a function of the density of air, ρ.
That is, even when air is used to dissipate heat generated from a heat source, the required volume flow rate of the air, {dot over (V)}, is varied depending on a variation in the density of the air, ρ.
FIG. 1 is a graph depicting a variation in the density of air depending on altitude.
Referring to FIG. 1, it can be seen that different volume flow rates of air are required to dissipate heat generated from a system in areas of different altitudes, respectively. For example, in an area at an altitude of 1,250 m, a volume flow rate of air is required which is larger than that of an area at an altitude of 0 m by about 13%. In an area at an altitude of 2,500 m, a volume flow rate of air is required which is larger than that of an area at an altitude of 0 m by about 28%.
To this end, conventionally, the design of a cooler for a system in which a heat source is present is made on the basis of an area where the density of air is low, namely, an area of a high altitude.
However, when the cooler design is made on the basis of an area of a high altitude, there is a possibility that system overcooling may occur in areas where the density of air is high. In such areas, there are additional problems of unnecessarily excessive power consumption and excessive noise.
In order to solve these problems, an altimeter is provided in conventional systems. In this case, the altimeter detects the altitude of the associated system. Based on the detected altitude, the rotating speed of a cooling fan for cooling the system is controlled. Thus, the system is cooled in a controlled manner.
In most conventional systems, expensive pressure meters are used for altimeters. For this reason, there is a problem in that an increase in system manufacturing costs occurs.
Taking into consideration the above-mentioned problem, a system only suitable for a low altitude and a system only suitable for a high altitude have been separately developed. A method has also been developed wherein the cooler of a system is tuned in accordance with a desired altitude when the system is delivered from a factory, so as to enable the cooler to appropriately cool the system at the desired altitude.
However, these methods have a problem in that they are unsuitable for notebook computers which are conveniently usable by virtue of their mobility and portability.